Machining apparatus with automatic restart function

Abstract

A laser cutting apparatus which allows cutting to be automatically restarted or redone without intervention from an operator once a cutting error or fault occurs. In a first embodiment, when the fault occurs the apparatus discontinues processing on the product corresponding to the fault. Thereafter, it moves to, and restarts cutting at, a starting position of the next product to be cut. In a second embodiment, the apparatus corrects a fault and continues cutting on the product corresponding to the fault by restarting cutting at the fault point. It determines whether a restart is possible at the point of the fault based on the type or definition of the fault. If a predetermined number of restarts are attempted at the point of fault without a successful restart, then the apparatus moves to a new start position. In another embodiment, the apparatus uses a profile sensor to prevent machine damage by sensing the position of the cutting head relative to the workpiece.

What is claimed is: 
     
       1. A machining apparatus for cutting products from a workpiece, comprising: laser beam means for generating a laser beam;   a cutting head for performing a cutting operation by focusing the laser beam onto the workpiece and by moving the laser beam relative to the workpiece along a desired path, in order to cut-out said products;   a cutting table for holding the workpiece; and   information processing means for controlling movement of said cutting head based on program blocks of information, said information processing means comprising: first memory means for storing cutting programs and data, said programs containing said program blocks which are used to control said cutting head;   second memory means for storing auxiliary function states and travel values for said cutting head;   fault detection means for detecting faults that occur during said cutting operation; and   restart means for automatically restarting the cutting operation based on said stored travel values and auxiliary function states, when said fault detection means detects a fault, by commanding the cutting head to move the laser beam from a current position to a restart position and to restart the cutting operation, said current position corresponding to a point on the workpiece at which the fault occurred and said restart position being based on the travel values stored in the second memory means.     
     
     
       2. A machining apparatus according to claim 1, wherein said information processing means further comprises: analyzing means for reading and analyzing each program block and for determining whether a program block being read corresponds to one of a restart position, a move command and an auxiliary function command, said restart means restarting the cutting operation when said analyzing means identifies a block that corresponds to a restart position.   
     
     
       3. A machining apparatus according to claim 2, wherein the restart position designated by the information processing means corresponds to one of an ending point of the program block being executed when the fault detection means detected the fault and a starting point of a program block identified by said analyzing means as corresponding to a restart position. 
     
     
       4. A machining apparatus according to claim 2, wherein said second memory means stores, as a travel value, a remaining travel distance corresponding to the program block being executed when the fault was detected, said remaining travel distance representing an amount of movement, designated by said executed program block, that the cutting head did not move before cutting was stopped s due to the fault, said information processing means storing said remaining travel distance when said fault is detected. 
     
     
       5. A machining apparatus according to claim 2, wherein said second memory means stores current auxiliary function states, which correspond to a condition of the apparatus when a fault is detected, in memory, said auxiliary function states including at least one of a radiation level of the laser beam, a profile function of the cutting head, and a cutting gas ON/OFF condition. 
     
     
       6. A machining apparatus according to claim 4, said information processing means further comprising: travel value operating means for changing the travel value stored in the second memory means, when the analyzing means identifies a block to be a move command, based on a value of the move command.   
     
     
       7. A machining apparatus according to claim 5, said information processing means further comprising: auxiliary function operating means for changing a state of one of said auxiliary functions stored in said second memory means, when the analyzing means identifies a block to be an auxiliary command, based on a value of said auxiliary command.   
     
     
       8. A laser cutting machine according to claim 1, further comprising: restart counting means for counting a number of restarts; and   restart position movement means for moving the cutting head relative to the workpiece to a restart position different from the position at which the fault occurred, when the number of restarts counted by said restart counting means exceeds a predetermined value.   
     
     
       9. A laser cutting machine according to claim 1, further comprising: fault recovery means for recovering from a fault state based on the identified type of fault; and   restart position movement means for moving the cutting head relative to the workpiece to a restart position, which differs from the position at which the fault occurred, said restart position being identified by program stored in memory.   
     
     
       10. A laser cutting machine for performing a cutting operation on a workpiece, comprising: a laser source for generating a laser beam;   a cutting head for using the laser beam to perform the cutting operation;   a cutting table, positioned near the cutting head, for holding the workpiece;   a fault detector for detecting faults in the cutting operation;   memory for storing a program, travel values and auxiliary function states; and   an information processing unit for controlling movement of said cutting head based on the program, said information processing unit comprising: a restart enable unit for determining, when a fault is detected, whether an automatic restart is selected;   a fault mode determining unit for identifying a fault type and for determining whether cutting can be automatically restarted after the identified fault type; and   a restarting unit for performing an automatic restart operation, when the automatic restart is selected and when the identified fault is of a type, from which cutting can be automatically restarted.     
     
     
       11. A laser cutting machine accordingly to claim 10, further comprising: a restart counter for counting a number of restarts; and   an alarm output unit for providing an alarm when the number of counted restarts has exceeded a predetermined value.   
     
     
       12. A laser cutting machine according to claim 10, further comprising: a restart counter for counting a number of restarts; and   a restart position movement unit for moving the cutting head relative to the workpiece to a restart position different from the position at which the fault occurred, when the number of restarts counted by said restart counting means exceeds a predetermined value.   
     
     
       13. A laser cutting machine according to claim 10, further comprising: fault recovery means for recovering from a fault state based on the identified type of fault; and   restart position movement means for moving the cutting head relative to the workpiece to a restart position, which differs from the position at which the fault occurred, said restart position being identified by program stored in memory.   
     
     
       14. A laser cutting machine according to claim 10, wherein the restart position is one of the starting point and end point of a block currently being executed. 
     
     
       15. A laser cutting machine for performing a cutting operation on a workpiece, comprising: a laser source for generating a laser beam;   a cutting head for using the laser beam to perform the cutting operation;   a cutting table, positioned near the cutting head, for holding the workpiece; a fault detector for detecting faults in the cutting operation; and   information processing means for controlling movement, said information processing means comprising: automatic restarting means for performing an automatic restart after a fault is detected;   restart status storing means for storing a current status information of the apparatus when an automatic restart is made, said current status information including at least one of a type of fault that was detected, a position of the cutting head when the fault was detected and the time at which the fault was detected; and   restart status displaying means for displaying said stored current status information.     
     
     
       16. A laser cutting machine according to claim 15, wherein the restart status displaying means displays a restart status together with a cutting shape on a graphic screen. 
     
     
       17. A laser cutting machine according to claim 15, further comprising: a profile sensor for detecting the position of the workpiece relative to the cutting head to identify a profiling fault.   
     
     
       18. A laser cutting machine for cutting products from a workpiece comprising: a laser oscillator for oscillating a laser beam;   a cutting head including a condenser for gathering the laser beam oscillated by said laser oscillator;   a cutting table for holding the workpiece;   means for detecting a fault and for stopping a cutting operation when a fault is detected and for storing a cutting stop position; and   move command means for commanding said cutting head to move to said cutting stop position   
     
     
       19. A laser cutting machine as set forth in claim 10, further comprising: restart counting means for counting a number of attempted restarts; and   alarm output means for determining a fault and providing an alarm if the number of attempted restarts counted by said restart counting means exceeds a predetermined number.   
     
     
       20. A laser cutting machine including a profiling function, comprising: means for storing a fault occurrence position at the occurrence of a profiling fault;   means for moving a cutting head to a reference position and checking a profile sensor signal;   means for returning the cutting head to said stored fault occurrence position; and   means for attempting a restart after the cutting head returns to the fault occurrence position.